Disclosed herein are branched polyarylene ether polymers and processes for preparing these polymers. More specifically, disclosed herein are methods for preparing branched polyarylene polymers by depolymerization of linear polyarylene ether polymers. One embodiment disclosed herein is directed to a process for preparing a branched polyarylene ether polymer which comprises (A) providing a reaction mixture which comprises (i) an optional solvent, (ii) a polyfunctional phenol compound of the formula Ar(OH)x wherein x≧3 and wherein Ar is an aryl moiety or an alkylaryl moiety, provided that
when Ar is an alkylaryl moiety at least three of the —OH groups are bonded to an aryl portion thereof, (iii) one or more linear polymers of the formula
wherein each m, independently of the others, is an integer of 0 or 1, each A, independently of the others, is
wherein R is a hydrogen atom, an alkyl group, an aryl group, an arylalkyl group, an alkylaryl group, or mixtures thereof,
wherein Rx is an alkylene group, an arylene group, an arylalkylene group, an alkylarylene group, or mixtures thereof,
or mixtures thereof, each B, independently of the others, is
wherein z is an integer of from 2 to about 20,
wherein u is an integer of from 1 to about 20,
wherein w is an integer of from 1 to about 20,
wherein each o, independently of the other, is an integer of 1, 2, 3, or 4,
wherein R1 and R2 each, independently of the other, are hydrogen atoms, alkyl groups, aryl groups, arylalkyl groups, alkylaryl groups, or mixtures thereof, and p is an integer of 0 or 1,
wherein b is an integer of 0 or 1,
wherein (1) Z is
wherein c is 0 or 1; (2) Ar′ is
(3) G is an alkyl group selected from alkyl groups containing from about 2 to about 10 carbon atoms; (4) Ar″ is
wherein s is 0, 1, or 2,
and (6) q is 0 or 1; or mixtures thereof, and n is an integer representing the number of repeat monomer units, (iv) optionally, a compound of the formula
wherein a is an integer of from 1 to 5 and R′ is a hydrogen atom, an alkyl group, an aryl group, an arylalkyl group, an alkylaryl group, or a mixture thereof, wherein two or more R′ groups can be joined together to form a ring, and (v) a carbonate base; and (B) heating the reaction mixture and removing generated water from the reaction mixture, thereby effecting a polymerization reaction.
In microelectronics applications, there is a great need for low dielectric constant, high glass transition temperature, thermally stable, photopatternable polymers for use as interlayer dielectric layers and as passivation layers which protect microelectronic circuitry. Poly(imides) are widely used to satisfy these needs; these materials, however, have disadvantageous characteristics such as relatively high water sorption and hydrolytic instability. There is thus a need for high performance polymers which can be effectively photopatterned and developed at high resolution.
Polyarylene ethers are known polymers for use as high performance engineering thermoplastics. They exhibit outstanding physical properties and high chemical resistance. The use of these materials as photoresists when substituted with photoactive substituents is also known. These materials are suitable for use in applications such as thermal ink jet printheads, other microelectronics applications, printed circuit boards, lithographic printing processes, interlayer dielectrics, and the like.
The formation and development of images on the surface of photoconductive materials by electrostatic means is well known. The basic electrophotographic imaging process, as taught by C. F. Carlson in U.S. Pat. No. 2,297,691, entails placing a uniform electrostatic charge on a photoconductive imaging member, exposing the imaging member to a light and shadow image to dissipate the charge on the areas of the imaging member exposed to the light, and developing the resulting electrostatic latent image by depositing on the image a finely divided electroscopic material known as toner. In charge area development (CAD) systems, the toner will normally be attracted to those areas of the imaging member which retain a charge, thereby forming a toner image corresponding to the electrostatic latent image. In discharge area development (DAD) systems, the toner will normally be attracted to those areas of the imaging member which have less or no charge as a result of exposure to light, thereby forming a toner image corresponding to the electrostatic latent image. This developed image may then be transferred to a substrate such as paper. The transferred image may subsequently be permanently affixed to the substrate by heat, pressure, a combination of heat and pressure, or other suitable fixing means such as solvent or overcoating treatment.
Imaging members for electrophotographic imaging systems comprising selenium alloys vacuum deposited on substrates are known. Imaging members have also been prepared by coating substrates with photoconductive particles dispersed in an organic film forming binder. Coating of rigid drum substrates has been effected by various techniques such as spraying, dip coating, vacuum evaporation, and the like. Flexible imaging members can also be manufactured by processes that entail coating a flexible substrate with the desired photoconducting material.
Some photoresponsive imaging members consist of a homogeneous layer of a single material such as vitreous selenium, and others comprise composite layered devices containing a dispersion of a photoconductive composition. An example of a composite xerographic photoconductive member is described in U.S. Pat. No. 3,121,006, which discloses finely divided particles of a photoconductive inorganic compound dispersed in an electrically insulating organic resin binder. Imaging members prepared according to the teachings of this patent contain a binder layer with particles of zinc oxide uniformly dispersed therein coated on a paper backing. The binders disclosed in this patent include materials such as polycarbonate resins, polyester resins, polyamide resins, and the like.
Photoreceptor materials comprising inorganic or organic materials wherein the charge generating and charge transport functions are performed by discrete contiguous layers are also known. Additionally, layered photoreceptor members are disclosed in the prior art, including photoreceptors having an overcoat layer of an electrically insulating polymeric material. Other layered photoresponsive devices have been disclosed, including those comprising separate photogenerating layers and charge transport layers as described in U.S. Pat. No. 4,265,990, the disclosure of which is totally incorporated herein by reference. Photoresponsive materials containing a hole injecting layer overcoated with a hole transport layer, followed by an overcoating of a photogenerating layer, and a top coating of an insulating organic resin, are disclosed in U.S. Pat. No. 4,251,612, the disclosure of which is totally incorporated herein by reference. Examples of photogenerating layers disclosed in these patents include trigonal selenium and phthalocyanines, while examples of transport layers include certain aryl diamines as illustrated therein.
In addition, U.S. Pat. No. 3,041,167 discloses an overcoated imaging member containing a conductive substrate, a photoconductive layer, and an overcoating layer of an electrically insulating polymeric material. This member can be employed in electrophotographic imaging processes by initially charging the member with an electrostatic charge of a first polarity, followed by exposing it to form an electrostatic latent image that can subsequently be developed to form a visible image.
U.S. Pat. No. 5,994,425 (Narang et al.), U.S. Pat. No. 6,022,095 (Narang et al.), EP 827027, and JP 10120743, the disclosures of each of which are totally incorporated herein by reference, disclose an improved composition comprising a photopatternable polymer containing at least some monomer repeat units with photosensitivity-imparting substituents, said photopatternable polymer being of the general formula
wherein x is an integer of 0 or 1, A is one of several specified groups, such as
B is one of several specified groups, such as
or mixtures thereof, and n is an integer representing the number of repeating monomer units. Also disclosed is a process for preparing a thermal ink jet printhead with the aforementioned polymer and a thermal ink jet printhead containing therein a layer of a crosslinked or chain extended polymer of the above formula.
U.S. Pat. No. 5,849,809 (Narang et al.), U.S. Pat. No. 6,203,143 (Narang et al.), EP 827028, and JP 10090895, the disclosures of each of which are totally incorporated herein by reference, disclose a composition which comprises (a) a polymer containing at least some monomer repeat units with photosensitivity-imparting substituents which enable crosslinking or chain extension of the polymer upon exposure to actinic radiation, said polymer being of the formula
wherein x is an integer of 0 or 1, A is one of several specified groups, such as
B is one of several specified groups, such as
or mixtures thereof, and n is an integer representing the number of repeating monomer units, wherein said photosensitivity-imparting substituents are hydroxyalkyl groups; (b) at least one member selected from the group consisting of photoinitiators and sensitizers; and (c) an optional solvent. Also disclosed are processes for preparing the above polymers and methods of preparing thermal ink jet printheads containing the above polymers.
U.S. Pat. No. 6,124,372 (Smith et al.), U.S. Pat. No. 6,151,042 (Smith et al.), U.S. Pat. No. 6,323,301 (Smith et al.), EP 827029, and JP 10097073, the disclosures of each of which are totally incorporated herein by reference, disclose a composition comprising a polymer with a weight average molecular weight of from about 1,000 to about 100,000, said polymer containing at least some monomer repeat units with a first, photosensitivity-imparting substituent which enables crosslinking or chain extension of the polymer upon exposure to actinic radiation, said polymer also containing a second, thermal sensitivity-imparting substituent which enables further crosslinking or chain extension of the polymer upon exposure to temperatures of about 140° C. and higher, wherein the first substituent is not the same as the second substituent, said polymer being selected from the group consisting of polysulfones, polyphenylenes, polyether sulfones, polyimides, polyamide imides, polyarylene ethers, polyphenylene sulfides, polyarylene ether ketones, phenoxy resins, polycarbonates, polyether imides, polyquinoxalines, polyquinolines, polybenzimidazoles, polybenzoxazoles, polybenzothiazoles, polyoxadiazoles, copolymers thereof, and mixtures thereof.
U.S. Pat. No. 5,889,077 (Fuller et al.), U.S. Pat. No. 6,087,414 (Fuller et al.), EP 827030, and JP 10090894, the disclosures of each of which are totally incorporated herein by reference, disclose a process which comprises reacting a polymer of the general formula
wherein x is an integer of 0 or 1, A is one of several specified groups, such as
B is one of several specified groups, such as
or mixtures thereof, and n is an integer representing the number of repeating monomer units, with (i) a formaldehyde source, and (ii) an unsaturated acid in the presence of an acid catalyst, thereby forming a curable polymer with unsaturated ester groups. Also disclosed is a process for preparing an ink jet printhead with the above polymer.
U.S. Pat. No. 5,739,254 (Fuller et al.), U.S. Pat. No. 5,753,783 (Fuller et al.), EP 826700, and JP 10087817, the disclosures of each of which are totally incorporated herein by reference, disclose a process which comprises reacting a polymer of the general formula
wherein x is an integer of 0 or 1, A is one of several specified groups, such as
B is one of several specified groups, such as
or mixtures thereof, and n is an integer representing the number of repeating monomer units, with an acetyl halide and dimethoxymethane in the presence of a halogen-containing Lewis acid catalyst and methanol, thereby forming a haloalkylated polymer. In a specific embodiment, the haloalkylated polymer is then reacted further to replace at least some of the haloalkyl groups with photosensitivity-imparting groups. Also disclosed is a process for preparing a thermal ink jet printhead with the aforementioned polymer.
U.S. Pat. No. 5,761,809 (Fuller et al.), EP 827026, and JP 10090896, the disclosures of each of which are totally incorporated herein by reference, disclose a process which comprises reacting a haloalkylated aromatic polymer with a material selected from the group consisting of unsaturated ester salts, alkoxide salts, alkylcarboxylate salts, and mixtures thereof, thereby forming a curable polymer having functional groups corresponding to the selected salt. Another embodiment is directed to a process for preparing an ink jet printhead with the curable polymer thus prepared.
U.S. Pat. No. 5,958,995 (Narang et al.), U.S. Pat. No. 6,184,263 (Narang et al.), EP 827031, and JP 10104836, the disclosures of each of which are totally incorporated herein by reference, disclose a composition which comprises a mixture of (A) a first component comprising a polymer, at least some of the monomer repeat units of which have at least one photosensitivity-imparting group thereon, said polymer having a first degree of photosensitivity-imparting group substitution measured in milliequivalents of photosensitivity-imparting group per gram and being of the general formula
wherein x is an integer of 0 or 1, A is one of several specified groups, such as
B is one of several specified groups, such as
or mixtures thereof, and n is an integer representing the number of repeating monomer units, and (B) a second component which comprises either (1) a polymer having a second degree of photosensitivity-imparting group substitution measured in milliequivalents of photosensitivity-imparting group per gram lower than the first degree of photosensitivity-imparting group substitution, wherein said second degree of photosensitivity-imparting group substitution may be zero, wherein the mixture of the first component and the second component has a third degree of photosensitivity-imparting group substitution measured in milliequivalents of photosensitivity-imparting group per gram which is lower than the first degree of photosensitivity-imparting group substitution and higher than the second degree of photosensitivity-imparting group substitution, or (2) a reactive diluent having at least one photosensitivity-imparting group per molecule and having a fourth degree of photosensitivity-imparting group substitution measured in milliequivalents of photosensitivity-imparting group per gram, wherein the mixture of the first component and the second component has a fifth degree of photosensitivity-imparting group substitution measured in milliequivalents of photosensitivity-imparting group per gram which is higher than the first degree of photosensitivity-imparting group substitution and lower than the fourth degree of photosensitivity-imparting group substitution; wherein the weight average molecular weight of the mixture is from about 10,000 to about. 50,000; and wherein the third or fifth degree of photosensitivity-imparting group substitution is from about 0.25 to about 2 milliequivalents of photosensitivity-imparting groups per gram of mixture. Also disclosed is a process for preparing a thermal ink jet printhead with the aforementioned composition.
U.S. Pat. No. 5,945,253 (Narang et al.), U.S. Pat. No. 6,365,323 (Narang et al.), EP 827033, and JP 10090897, the disclosures of each of which are totally incorporated herein by reference, disclose a composition which comprises a polymer containing at least some monomer repeat units with photosensitivity-imparting substituents which enable crosslinking or chain extension of the polymer upon exposure to actinic radiation, said polymer being of the formula
wherein x is an integer of 0 or 1, A is one of several specified groups, such as
B is one of several specified groups, such as
or mixtures thereof, and n is an integer representing the number of repeating monomer units, wherein said photosensitivity-imparting substituents are allyl ether groups, epoxy groups, or mixtures thereof. Also disclosed are a process for preparing a thermal ink jet printhead containing the aforementioned polymers and processes for preparing the aforementioned polymers.
U.S. Pat. No. 5,863,963 (Narang et al.), U.S. Pat. No. 6,090,453 (Narang et al.), and JP 10090899, the disclosures of each of which are totally incorporated herein by reference, disclose a process which comprises the steps of (a) providing a polymer containing at least some monomer repeat units with halomethyl group substituents which enable crosslinking or chain extension of the polymer upon exposure to a radiation source which is electron beam radiation, x-ray radiation, or deep ultraviolet radiation, said polymer being of the formula
wherein x is an integer of 0 or 1, A is one of several specified groups, such as
B is one of several specified groups, such as
or mixtures thereof, and n is an integer representing the number of repeating monomer units, and (b) causing the polymer to become crosslinked or chain extended through the photosensitivity-imparting groups. Also disclosed is a process for preparing a thermal ink jet printhead by the aforementioned curing process.
U.S. Pat. No. 6,007,877 (Narang et al.), U.S. Pat. No. 6,273,543 (Narang et al.), EP 827032, and JP 10090898, the disclosures of each of which are totally incorporated herein by reference, disclose a composition which comprises a polymer containing at least some monomer repeat units with water-solubility- or water-dispersability-imparting substituents and at least some monomer repeat units with photosensitivity-imparting substituents which enable crosslinking or chain extension of the polymer upon exposure to actinic radiation, said polymer being of the formula
wherein x is an integer of 0 or 1, A is one of several specified groups, such as
B is one of several specified groups, such as
or mixtures thereof, and n is an integer representing the number of repeating monomer units. In one embodiment, a single functional group imparts both photosensitivity and water solubility or dispersability to the polymer. In another embodiment, a first functional group imparts photosensitivity to the polymer and a second functional group imparts water solubility or dispersability to the polymer. Also disclosed is a process for preparing a thermal ink jet printhead with the aforementioned polymers.
U.S. Pat. No. 5,814,426 (Fuller et al.), EP 918257, and JP 11218943, the disclosures of each of which are totally incorporated herein by reference, disclose an imaging member which comprises a conductive substrate, a photogenerating material, and a binder which comprises a polymer of the formulae I, II, III, IV, V, VI, VII, VIII, IX, or X as further defined therein.
U.S. Pat. No. 5,882,814 (Fuller et al.), EP 918256, and JP 11223956, the disclosures of each of which are totally incorporated herein by reference, disclose an imaging member which comprises a conductive substrate, a photogenerating layer, and a charge transport layer comprising a polymer of the formulae I, II, III, IV, V, VI, VII, VIII, IX, or X as further defined therein.
U.S. Pat. No. 5,874,192 (Fuller et al.), EP 918258, and JP 11223955, the disclosures of each of which are totally incorporated herein by reference, disclose an imaging member which comprises a conductive substrate, a photogenerating material, a charge transport material, and a polymeric binder comprising (a) a first polymer comprising a polycarbonate, and (b) a second polymer of the formulae I, II, III, IV, V, VI, VII, VIII, IX, or X as further defined therein.
U.S. Pat. No. 6,273,985 (DeLouise et al.), the disclosure of which is totally incorporated herein by reference, discloses a process for bonding a first article to a second article which comprises (a) providing a first article comprising a polymer having photosensitivity-imparting substituents; (b) providing a second article comprising metal, plasma nitride, silicon, or glass; (c) applying to at least one of the first article and the second article an adhesion promoter selected from silanes, titanates, or zirconates having (i) alkoxy, aryloxy, or arylalkyloxy functional groups and (ii) functional groups including at least one photosensitive aliphatic >C═C< linkage; (d) placing the first article in contact with the second article; and (e) exposing the first article, second article, and adhesion promoter to radiation, thereby bonding the first article to the second article with the adhesion promoters. In one embodiment, the adhesion promoter is employed in microelectrical mechanical systems such as thermal ink jet printheads.
U.S. Pat. No. 6,260,956 (Narang et al.), the disclosure of which is totally incorporated herein by reference, discloses an ink jet printhead which comprises (i) an upper substrate with a set of parallel grooves for subsequent use as ink channels and a recess for subsequent use as a manifold, the grooves being open at one end for serving as droplet emitting nozzles, and (ii) a lower substrate in which one surface thereof has an array of heating elements and addressing electrodes formed thereon, said lower substrate having an insulative layer deposited on the surface thereof and over the heating elements and addressing electrodes and patterned to form recesses therethrough to expose the heating elements and terminal ends of the addressing electrodes, the upper and lower substrates being aligned, mated, and bonded together to form the printhead with the grooves in the upper substrate being aligned with the heating elements in the lower substrate to form droplet emitting nozzles, said upper substrate comprising a material formed by crosslinking or chain extending a polymer of formula I or II.
U.S. Pat. No. 6,117,967 (Fuller et al.) and JP 200119761, the disclosures of each of which are totally incorporated herein by reference, discloses a polymer of the formula
wherein A is
or a mixture of
wherein R is a hydrogen atom, an alkyl group, an aryl group, or mixtures thereof, B is one of specified groups, such as
or mixtures thereof, and n is an integer representing the number of repeating monomer units.
U.S. Pat. No. 6,177,238 (Fuller et al.), the disclosure of which is totally incorporated herein by reference, discloses an ink jet printhead containing a polymer of the formula
wherein P is a substituent which enables crosslinking of the polymer, a, b, c, and d are each integers of 0, 1, 2, 3, or 4, provided that at least one of a, b, c, and d is equal to or greater than 1 in at least some of the monomer repeat units of the polymer, A is
or a mixture of
wherein R is a hydrogen atom, an alkyl group, an aryl group, or mixtures thereof, B is one of specified groups, such as
or mixtures thereof, and n is an integer representing the number of repeating monomer units.
U.S. Pat. No. 6,174,636 (Fuller et al.), the disclosure of which is totally incorporated herein by reference, discloses an imaging member which comprises a conductive substrate, a photogenerating material, and a binder comprising a polymer of the formula
wherein A is
or a mixture of
wherein R is a hydrogen atom, an alkyl group, an aryl group, or mixtures thereof, B is one of specified groups, such as
or mixtures thereof, and n is an integer representing the number of repeating monomer units.
U.S. Pat. No. 6,187,512 (Foucher et al.) and JP 2000344884, the disclosures of each of which are totally incorporated herein by reference, disclose a process which comprises reacting a polymer of the general formula
wherein x is an integer of 0 or 1, A is one of several specified groups, such as
B is one of several specified groups, such as
or mixtures thereof, and n is an integer representing the number of repeating monomer units, with a halomethyl alkyl ether, an acetyl halide, and methanol in the presence of a halogen-containing Lewis acid catalyst, thereby forming a halomethylated polymer.
U.S. Pat. No. 6,020,119 (Foucher et al.), the disclosure of which is totally incorporated herein by reference, discloses a process which comprises reacting a polymer of the general formula
wherein x is an integer of 0 or 1, A is one of several specified groups, such as
B is one of several specified groups, such as
or mixtures thereof, and n is an integer representing the number of repeating monomer units, with a halomethylethyl ether, a hydrohalic acid, and acetic acid in the presence of a halogen-containing Lewis acid catalyst, thereby forming a halomethylated polymer.
U.S. Pat. No. 6,139,920 (Smith et al.) and U.S. Pat. No. 6,260,949 (Smith et al.), the disclosures of each of which are totally incorporated herein by reference, disclose a composition comprising a blend of (a) a thermally reactive polymer selected from the group consisting of resoles, novolacs, thermally reactive polyarylene ethers, and mixtures thereof; and (b) a photoreactive epoxy resin that is photoreactive in the absence of a photocationic initiator.
U.S. Pat. No. 5,773,553 (Fuller et al.) and U.S. Pat. No. 5,869,595 (Fuller et al.), the disclosures of each of which are totally incorporated herein by reference, disclose a process which comprises reacting a polyimide precursor with borane. Also disclosed is a thermal ink jet printhead containing a layer comprising the product of this reaction.
U.S. Pat. No. 5,939,206 (Kneezel et al.) and JP 10100410, the disclosures of each of which are totally incorporated herein by reference, disclose an apparatus which comprises at least one semiconductor chip mounted on a substrate, said substrate comprising a porous, electrically conductive member having electrophoretically deposited thereon a coating of a polymeric material. In one embodiment, the semiconductor chips are thermal ink jet printhead subunits.
U.S. Pat. No. 6,485,130 (DeLouise et al.), the disclosure of which is totally incorporated herein by reference, discloses a process for bonding a first article to a second article which comprises (a) providing a first article comprising a polymer having photosensitivity-imparting substituents; (b) providing a second article comprising metal, plasma nitride, silicon, or glass; (c) applying to at least one of the first article and the second article an adhesion promoter selected from silanes, titanates, or zirconates having (i) alkoxy, aryloxy, or arylalkyloxy functional groups and (ii) functional groups including at least one photosensitive aliphatic >C═C< linkage; (d) placing the first article in contact with the second article; and (e) exposing the first article, second article, and adhesion promoter to radiation, thereby bonding the first article to the second article with the adhesion promoter. In one embodiment, the adhesion promoter is employed in microelectrical mechanical systems such as thermal ink jet printheads.
“Cyclodepolymerisation of bisphenol A polysulfone: evidence for self-complementarity in macrocyclic poly(ether sulfones),” Ian Baxter et al., Chem. Commun., 1998, page 2213, the disclosure of which is totally incorporated herein by reference, discloses bisphenol A polysulfone undergoing fluoride-promoted cyclodepolymerisation; high molar mass polymer was thus transformed into a series of macrocyclic oligomers containing up to at least 72 aromatic rings; those containing up to 24 rings were isolated as pure compounds, and single-crystal X-ray studies of the cyclotrimer and cyclotetramer revealed shape-complementary pairs and chains of macrocyles, respectively.
“Hyperbranched Polymers 10 Years After,” Y. H. Kim, Journal of Polymer Science: Part A: Polymer Chemistry, Vol. 36, 1685–1698 (1998), the disclosure of which is totally incorporated herein by reference, discloses that hyperbranched polymers, as well as dendrimers, may find utilities in the areas where the structural uniqueness of these polymers gives merit. There has been much progress in the structural understanding and the methods of synthesis of these polymers. However, functional understanding and utility of these polymers are still in infancy. Better understanding on physical properties of these polymers, such as solubility and miscibility of these polymers in solvents or with polymers, and functional group dependency to the thermal relaxation process are needed for further development of the subject.
“Randomly Branched Bisphenol A Polycarbonates. I. Molecular Weight Distribution Modeling, Interfacial Synthesis, and Characterization,” M. J. Marks et al., Journal of Polymer Science: Part A: Polymer Chemistry, Vol. 38, 560–570 (2000), the disclosure of which is totally incorporated herein by reference, discloses that randomly branched bisphenol A polycarbonates (PCs) were prepared by interfacial polymerization methods to explore the limits of gel-free compositions available by the adjustment of various composition and process variables. A molecular weight distribution (MWD) model was devised to predict the MWD, G, and weight-average molecular weight per arm (Mw/arm) values based on the composition variables. The amounts of the monomer, branching agent, and chain terminator were adjusted such that the weight-average functionality of the phenolic monomers (FOH) was less than 2 to preclude gel formation in both the long- and short-chain branched (SCB) PCs. Several series of SCB and long-chain branched PCs were prepared, and those lacking gels showed molecular weights measured by gel permeation chromatography-UV and gel permeation chromatography-LS consistent with model calculations. In SCB PCs, the minimum Mw/arm that could be realized without gel formation depended on both composition (molecular weight, terminator type) and process (terminator addition point, coupling catalyst) variables. The minimum Mw/arm achieved in the low molecular weight series studied ranged from ˜3300 to ˜1000. The use of long chain alkyl phenol terminators gave branched PCs with lower glass-transition temperatures but a higher gel-free minimum Mw/arm. SCB PCs where Mw/arm was less than ˜Mc spontaneously cracked after compression molding, a result attributed to their lack of polymer chain entanglements.
“Hyperbranched poly(arylene ether phosphine oxide)s,” H. S. Lee et al., Polymer Bulletin, 45, 319–326 (2000), the disclosure of which is totally incorporated herein by reference, discloses that new AB2 and A2B monomers, bis(4-fluorophenyl)-4′-hydroxyphenylphosphine oxide and bis(4-hydroxyphenyl)-4′-fluorophenyl-phosphine oxide, were prepared and converted to corresponding hyperbranched poly(arylene ether phosphineoxide)s with hydroxyphenyl and fluorophenyl end functional groups. While the dihydroxy monomer gave a low molecular weight polymer, the difluoro monomer produced a high molecular weight hyperbranched polymer. The glass transition temperature of the obtained polymers was 266° C. and 230° C., and 5% weight loss temperature was 491° C. and 391° C., respectively. The fluorophenyl-terminated hyperbranched polymer was soluble in CHCl3, but the hydroxyphenyl-terminated polymer was not soluble in CHCl3 even though it has lower molecular weight than the fluorophenyl-terminated polymer, indicating that properties of the hyperbranched polymers markedly depend on end functional groups as well as their molecular weight.
Hyperbranched polymers and processes for the preparation thereof are known. Known syntheses, however, frequently entail the use of custom-synthesized monomers, which can take, for example, two to five steps to prepare prior to synthesis of the hyperbranched polymer. Accordingly, processes which enable the preparation of branched polyarylene ether polymers by simpler processes are desirable. Hyperbranched polymers can have several advantages over linear polymers of the same class. For example, branched polymers (hyperbranches and dendrimers) can exhibit a lower solution and melt viscosities compared to their linear analogs owing to their lower hydrodynamic volume for the same molecular weight. In addition, hyperbranched polymers are often more soluble than their linear analogs, which is thought to be attributable to a decrease in the ability of the polymeric material to intertwine at a molecular level. Further, hyperbranched polymers can be thought to be a mid-point between linear polymers and crosslinked polymers, since severing of or more of the branches will not result in a large loss of molecular weight.
Accordingly, while known compositions and processes are suitable for their intended purposes, a need remains for branched polyarylene ether polymers. In addition, a need remains for methods for preparing branched polyarylene ether polymers. Further, a need remains for methods for preparing branched polyarylene ether polymers wherein the synthesis can be carried out by depolymerization of linear polymers. There is also a need for methods for preparing branched polyarylene ether polymers that enables control of the degree of branching within the polymer and the introduction of branching in a well-defined manner. In addition, there is a need for methods for preparing branched polyarylene ether polymers that can be carried out at desirably low cost levels. Further, there is a need for methods for preparing branched polyarylene ether polymers wherein variations in the ratio of monomers can result in control over the degree of branching and the length of the linear units. Additionally, there is a need for improved photosensitive imaging members. A need also remains for improved binders for photosensitive imaging members. In addition, there is a need for polymeric binders suitable for use in photogenerating layers in imaging members. Further, a need remains for polymeric binders suitable for use in charge transport layers in imaging members. Additionally, a need remains for polymeric binders suitable for use in photosensitive imaging members that can, in some embodiments, impart improved wear resistance to the members, particularly under bias charging roll charging conditions. There is also a need for polymeric binders suitable for use in photosensitive imaging members that can solubilize charge transport materials and other small molecule dopants used to tailor the physical and/or mechanical properties of the imaging members.